Before we begin, in the UK cats are considered property and as such should not be trapped without their owners consent.

Don't start thinking about buying a feral cat trap to catch a feral cat
make sure the cat is a feral. Many cats have been abandoned by their owners,
and have not been altered. These cats have litters of kittens, who, if
not handled by humans, become feral. Ask next door if its their cat,
put an add in the local newspaper, local shop or lamppost's along your
street. Ask around first BEFORE deciding to trap, if it is someone's cat, any unjustified
control may lead to your prosecution.

folded cat trap and assembled cat trap

That said we do sell a lot of cat traps to public authorities, MOD, cats protection, T.N.R & private individuals in this country and throughout Spain, Portugal, Belgium, Netherlands, France, Germany & beyond.